Characterization of Fe3Si-based coatings on low silicon steel by pulsed Nd：YAG laser cladding

The Fe3Si based coating was produced on the Fe-1Si steel surface by a pulsed Nd:YAG (yttrium aluminum garnet) laser. Its phase constitution and microstructure were characterized by using X-ray diffraction (XRD),optical microscope (OM),and field emission scanning electron microscope (FESEM) with associated energy dispersive spectroscopy (EDS) and transmission electron microscopy (TEM). The hyperfine structure of the coating was studied by Mssbauer spectra (MS) and the magnetic property was also measured at ...     

Effect of Heat Treatmeut OH Crystallization of Nd：YAG Ceramics

（Nd0.01Y0.99）3Al5O12 nano-sized powders were synthesized by low temperature combustion （LCS）, using Nd2O3, Y2O3, Al（NO3）3.9H2O, ammonia water and citric acid as starting materials. The powders were characterized by TG-DTA, XRD, FT-IR, ICP and TEM, respectively. The grain sizes were calculated by the Scherrer＇s formula using the full width at half maximum （FWHM） of YAG （420） crystal plane diffraction lines. The study focused on crystallization of ceramics at different heat treatment temperatures. The experimental results show that crystallizing temperature of YAG is 850 ℃, and the intermediate crystal phase YAP, appearing during heat treatment, transforms to YAG cubic crystal phase at the temperature of 1 050℃. The particle size of the powders synthesized by LCS is nano-sized. With the temperature increasing, the mean grain sizes raise, the stand deviations keep almost at the value of 2.0 and the lattice parameters decrease. The grains mainly grow by grain boundary diffusion. The lattice parameter expansion is caused by an increase of the repulsive dipolar interactions on surfaces of crystallites,     

Nd:YAG激光和CO2激光熔敷性能比较研究

从Maxwell方程和Hagen-Ruben公式出发,计算了Nd：YAG激光(波长为1．06μm)和CO2激光(波长为10．6μm)在金属中的吸收率和穿透深度,并做了Nd：YAG激光与CO2激光的熔敷试验比较．结果表明：Nd：YAG激光在金属中吸收率约为CO2激光的3倍,更适于激光熔敷;CO2激光在金属中穿透力约为Nd：YAG激光的3倍,更适于激光相变淬火．     

Nd:YAG激光医学应用的技术研究

激光在目前医学领域上应用最广泛的当属Nd:YAG医用激光器,对Nd:YAG激光治疗机的物理光学机理、系统结构等进行了研究,并就光学系统、机械结构设计方面等提出改进措施.     

45#钢表面NiCrBSi合金激光熔敷层的组织和硬度

为提高45^#钢表面硬度及耐磨性能，采用激光熔敷技术在其表面制备NiCrBSi合金涂层，利用X射线衍射仪、扫描电镜和透射电镜分析了熔敷层的微观组织，利用显微硬度计测试了熔敷层的硬度，结果表明，激光熔敷层的组织由γ-Ni树枝晶、γ-Ni Ni3B共晶、M7C3树枝晶和CrB颗粒组成，激光熔敷层的硬度在HV800～900之间．     

Investigation on laser cladding of MoSi2 powder on steel

The feasibility of the fabrication of coatings for elevated-temperature structural applications by laser cladding MoSi2 pow- der on steel was investigated. A dense and crack-free fine coating, well-bonded with the substrate has been obtained by this technique This coating consists of FeMoSi, Fe2Si and a small amount of MosSi3 due to dilution of the substrate in the coating. The microstructure of the coating is characterized of typical fine dendrites, The dendrites are composed of FeMoSi primary phase, and the interdendritic areas are two eutectic phases of FeMoSi and Fe2Si. The hardness of the coating reaches 845 Hv0.5, 3.7 times larger than that of the steel substrate （180 Hv05）.     

硝酸盐热分解法制备Nd:YAG透明激光陶瓷

以Al(NO₃)₃9H₂O,Y(NO₃)₆H₂O和Nd₂O₃为原料,采用硝酸盐热分解法在1000℃左右合成了单相Nd:YAG陶瓷超细粉体．加入0.5％的正硅酸乙酯作为烧结添加剂后,前驱粉料经1500℃~1700℃真空热压烧结5h得到具有一定透明度的掺钕钇铝石榴石多晶陶瓷．采用X射线衍射仪(XRD)及扫描电子显微镜(SEM)等测试手段对Nd:YAG陶瓷材料进行了测试,结果表明当焙烧温度为1000℃时,前驱粉体可以直接得到YAG立方晶相,没有YAM和YAP等中间相生成,煅烧所得的粉末颗粒细小均匀,呈椭球状,颗粒尺寸为200~250nm,且分散性较好．真空烧结后的陶瓷晶粒尺寸在2~4μm,并且随着烧结温度的提高,Nd:YAG陶瓷的晶粒增大,晶形发育完整,气孔减少,晶粒内部和晶界的化学组成基本相同．所制备的Nd:YAG透明陶瓷在可见光区最大透光率为47％,在红外光区的透光率接近56％．     

高电力二极管Nd：YAG激光器的最佳共振条件

对高电力二级管Nd:YAG激光器的输出功率和偏光特性进行图表分析.介绍了平行-评判共振器的结构,讨论了根据偏光方向的热焦点和热弹性产生的热效果问题.在原有的输出功率下,能保持稳定的激光输出的最佳共振条件,同时对非对称构成的高电力Nd:YAG激光共振器在理论上预测的光共振条件和实验结果进行了比较.     

Nd:YAG调Q脉冲激光器微孔实验研究

为了输出高功率、高光束质量的脉冲激光以及制备高质量微孔,对平凸非稳腔结构进行了理论分析,给出了腔参数变化曲线.设计出了高功率、高光束质量的平凸非稳腔灯泵浦脉冲Nd:YAG调Q激光器.激光脉冲能量为500 m J,峰值功率达到5 MW,光束参数积优于4.2 mm.m rad.分别在0.04~0.07 mm厚度金属碳钢及1mm厚度非金属陶瓷上进行了微孔打孔实验,得到了百微米微孔.     

连续抽运Nd:YAG激光高重频电光调Q研究

介绍了在连续闪光灯抽运的Nd:YAG激光器中应用电光调Q技术,实现了重复频率1～5kHz的窄脉冲激光输出,脉冲宽度14～15ns,为连续、准连续抽运的Nd:YAG激光器提供一种新的调Q技术.     

高效率侧面泵浦国产Nd:YAG陶瓷激光器

研究了808nm侧面泵浦国产Nd:YAG陶瓷棒的激光输出特性和热透镜效应,并与相同尺寸、相同掺杂浓度的Nd:YAG晶体进行了对比。当泵浦功率为60W时,陶瓷获得了21.6W的1064nm连续激光输出,光-光转换效率为36%,斜效率达到46.9%,在相同的泵浦条件下,Nd:YAG晶体的输出功率为23.9W,光-光转换效率为39.8%,斜效率为50.3%。实验结果表明,Nd:YAG陶瓷的性能已经接近于Nd:YAG晶体。